1. Technical Field
The present invention relates to a photoelectric conversion device, and, more particularly, to a photoelectric conversion device including a signal processing circuit associated with a respective one of columns of a pixel array.
2. Description of the Related Art
Imaging apparatuses for performing signal processing in parallel, the apparatuses having a signal processing circuit for each column in a pixel array or for a plurality of columns in the pixel array arranged in a matrix are known.
Japanese Patent Application Laid-Open No. 2010-147684 discusses an imaging apparatus having, as a signal processing device provided for each column in a pixel array, an analog-digital (A/D) conversion unit, and a memory for storing the conversion result, and a block output line for each block of a plurality of memories. A digital signal appearing on the block output line is transmitted to a latter stage in synchronization with a clock signal by a synchronization circuit.
Meanwhile, as a method for supplying a driving signal, a buffer circuit tree structure for connecting buffer circuits in a tree shape has been known.
Japanese Patent Application Laid-Open No. 2010-147684 has no description about how a signal for driving the signal processing circuits or the synchronization circuits is supplied. If it is assumed that, in the imaging apparatus discussed in Japanese Patent Application Laid-Open No. 2010-147684, the driving signal is supplied using the buffer circuit tree structure, the number of simultaneously operating buffer circuits increases, and this may cause an increase in transitional current consumption. The transitional increase in current consumption causes increase in voltage fluctuations due to impedance in a power supply line of the imaging apparatus. This may narrow the operation margin range of the imaging apparatus and increase the amount of noise.